The creator of the ProBox, munkustrap, did this and shared this page at some point:
http://www.weritz.com/probox/PS_for_console_only.pdf@arjepsen on here also did this successfully, from what I understand. But I think there were some heat-issues afterwards, but I don't remember the details (and can't find the original thread right now).
This is WAY too challenging a project for my skill level, but if you're a (semi-)pro with electrical and electronic circuits and wiring, it should be possible